Electroplating has many applications. One very important developing application is in electroplating copper onto semiconductor wafers to form conductive copper lines for “wiring” individual devices of the integrated circuit. Often this electroplating process serves as a step in the damascene fabrication procedure.
For example, wafers are inserted in a substrate holder and then immersed into an electroplating bath to perform the electroplating process. After the electroplating process is completed, the wafers are removed from the electroplating bath. However, after electroplating of several batches of wafers, contamination is found on the substrate holder, which may induce inline gap-filling defects during the electroplating process, and thus to deteriorate the process yield. What is needed therefore is improved technology for removing the contamination on the substrate holder.